A cellular communications network can include a radio network made up of a number of fixed-location transceivers, also known as base stations or “cell towers.” Each cell tower can serve a geographic area or a “cell.” Cells of the cellular communications network can be grouped into location areas. For example, in a cellular network based on Global System for Mobile communications (GSM) technology, a location area can correspond to a group of cells sharing a Base Station Controller (BSC). Tens or hundreds of cells can share a single BSC, which can handle allocation of radio channels, receive measurements from mobile devices in the cells, and control handovers from cell to cell. The actual geographic area covered by a cell or a location area can vary, for example, between urban and rural areas, and from one cellular service provider to another. A unique number, or “location area code” (LAC), can be assigned to each location area to identify the location area.
Multiple mobile devices (e.g., cellular phones) can connect to each cell tower. If a mobile device is wirelessly connected to a cell tower, the mobile device “knows” the cell tower to which the mobile device is currently connected by an identifier of the cell tower (e.g., a cell identifier). The mobile device can also know a current LAC designating a current location area in which the mobile device is located. If the mobile device moves between cells or location areas, the cell identifier and current LAC can be updated automatically for the mobile device. The mobile device can update the current location area code without having to maintain an active wireless connection to a cell tower.